Functions and Errors

Option

A Value That May Be Missing

Option<T> is Some(value) or None. Iterator searches return Option, and match handles both cases.

Program

Play the program to find the first value over 15.

option.rs 
fn main() {
    let nums = vec![10, 20, 30];
    let found = nums.iter().find(|&&n| n > 15);
    let value = match found {
        Some(n) => *n,
        None => 0,
    };
    println!("{value}");
}
Option `Option<T>` models a value that may be absent.
find `find` returns `Some` for the first match, else `None`.
match Handling `Some` and `None` is required to read the value.